CN111373008A

CN111373008A - Release liner for laser cut adhesive

Info

Publication number: CN111373008A
Application number: CN201880075056.XA
Authority: CN
Inventors: 安德鲁·J·施托克霍尔姆; 乔舒亚·J·洛加; 艾伯特·I·埃费拉茨
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2017-11-21
Filing date: 2018-11-19
Publication date: 2020-07-03
Anticipated expiration: 2038-11-19
Also published as: KR20200087806A; WO2019103955A1; US20200347273A1; CN111373008B

Abstract

Various embodiments described herein relate to laminates. The laminate includes a release liner comprising at least one polyolefin and an adhesive layer. The adhesive layer contacts an area of the first major surface of the release liner. Upon exposure to laser electromagnetic radiation, the adhesive layer is configured to absorb at least 55% (in some embodiments at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even 100%) of the laser electromagnetic radiation, and the release liner absorbs no greater than 45% (in some embodiments no greater than 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or even 0%) of the laser electromagnetic radiation.

Description

Release liner for laser cut adhesive

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional patent application No. 62/589266, filed on 21/11/2017, the disclosure of which is incorporated herein by reference in its entirety.

Background

The adhesive may be deposited on a release liner prior to application to the final substrate. The adhesive may be cut into a predetermined shape prior to application to the final substrate. However, cutting the adhesive (e.g., cutting the adhesive with a laser) may result in cutting or at least melting a portion of the release liner, which may result in a tighter bond being formed between the adhesive and the release liner. When the release liner is removed, breaking the tight bond between the adhesive and the release liner may cause the adhesive to remain adhered to the release liner, thereby damaging the adhesive layer.

Disclosure of Invention

Various embodiments disclosed relate to laminates. In one aspect, a laminate comprises:

a release liner comprising at least one polyolefin; and

an adhesive layer contacting a region of the first major surface of the release liner,

wherein upon exposure to laser electromagnetic radiation, the adhesive layer is configured to absorb at least 55% (in some embodiments at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even 100%) of the laser electromagnetic radiation, and the release liner absorbs no greater than 45% (in some embodiments no greater than 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or even 0%) of the laser electromagnetic radiation.

In a second aspect, a method of processing a laminate is disclosed. The method can comprise the following steps:

providing or receiving: a release liner comprising at least one polyolefin; and an adhesive layer contacting a region of the first major surface of the release liner,

wherein upon exposure to laser electromagnetic radiation, the adhesive layer is configured to absorb at least 55% (in some embodiments at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even 100%) of the laser electromagnetic radiation, and the release liner absorbs no greater than 45% (in some embodiments no greater than 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or even 0%) of the laser electromagnetic radiation; and

the laminate is exposed to a source of laser electromagnetic radiation having a wavelength in the range of 0.10 to 15 microns (in some embodiments in the range of 0.2 to 14 microns, in the range of 0.3 to 13 microns, in the range of 8 to 12 microns, or even in the range of 9 to 11 microns) to form openings through the optically clear adhesive.

Various exemplary embodiments of the present disclosure provide certain advantages, some of which are unexpected. According to various embodiments of the present disclosure, an adhesive coated on a subsequently cut polyolefin-free liner (such as a polyethylene terephthalate liner, paper liner, or copolyester liner) may cause the edges of the cut adhesive to melt or burn and subsequently bond to the bottom of the polyolefin-free liner, such as a polyethylene terephthalate liner. According to various embodiments, a polyolefin-free liner or a polyethylene terephthalate liner may be replaced with a liner comprising a polyolefin, such as polypropylene, which may be cut at a different wavelength than the adhesive, thereby avoiding melting of the liner and bonding with the adhesive. According to various embodiments of the present disclosure, cutting the adhesive against the polyolefin liner, as opposed to not containing a polyolefin liner or a polyethylene terephthalate liner, can create a light tack around the edge of a component that can be used as a transport aid as opposed to a stronger bond, such that the peel force required to remove a first liner can be equal to or greater than the peel force required to remove a second liner without causing confusion of the liners. According to various embodiments of the present disclosure, adhesives cut against polyolefin liners may be successfully integrated in exemplary electronic devices, such as flexible electronic devices, because the lack of a tight bond formed against a polyolefin-containing liner results in less damage to the adhesive and lower peel forces than corresponding adhesives cut against a polyolefin-free liner (e.g., comprising polyethylene terephthalate). According to various embodiments, an adhesive that is damaged by removing the adhesive from an unpolymerized polyolefin liner or a polyethylene terephthalate liner may result in an adhesive layer having reduced or unacceptable optical properties. According to various embodiments, the lower peel force may also help prevent damage to brittle substrates such as optical light emitting diode panels when the liner must be removed from the adhesive. Further, according to various embodiments, damage to the adhesive layer due to loss of material may render it unusable for lamination. According to various embodiments, an adhesive that is damaged by removing the adhesive from an unpolymerized polyolefin liner or polyethylene terephthalate may result in an adhesive layer having reduced strength or resiliency. In addition, according to various embodiments, damaging the adhesive may make it difficult to cut the adhesive into the appropriate shape.

Drawings

The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in this document.

Fig. 1 is a cross-sectional view of an exemplary laminate described herein.

Fig. 2 is a cross-sectional view of another exemplary laminate described herein.

Fig. 3 is a cross-sectional view of an exemplary electronic device described herein.

Fig. 4 is a photograph of a cross-section of the exemplary laminate of fig. 2 described herein.

Fig. 5 is a photograph of a cross-section of another exemplary laminate described herein.

Detailed Description

Reference will now be made in detail to specific embodiments of the presently disclosed subject matter, examples of which are illustrated in the accompanying drawings. While the presently disclosed subject matter will be described in conjunction with the recited claims, it will be understood that the exemplary subject matter is not intended to limit the claims to the disclosed subject matter.

Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not only about 0.1% to about 5%, but also include individual values (e.g., 1%, 2%, 3%, and 4%) and sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise indicated, the expression "about X to Y" has the same meaning as "about X to about Y". Likewise, unless otherwise indicated, the expression "about X, Y or about Z" has the same meaning as "about X, about Y, or about Z".

In this document, the terms "a", "an" or "the" are used to include at least one unless the context clearly indicates otherwise. The term "or" is used to refer to a non-exclusive "or" unless otherwise indicated. The expression "at least one of a and B" has the same meaning as "A, B or a and B". Also, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid in the understanding of the document and should not be construed as limiting; information related to a section header may appear within or outside of that particular section.

In the methods described herein, various actions may be performed in any order, except when a time or sequence of operations is explicitly recited, without departing from the principles of the present disclosure. Further, the acts specified may occur concurrently unless the express claim language implies that they occur separately. For example, the claimed act of performing X and the claimed act of performing Y may be performed simultaneously in a single operation, and the resulting process would fall within the literal scope of the claimed process.

As used herein, the term "about" can allow for a degree of variability in a value or range, e.g., within 10%, within 5%, or within 1% of the stated value or limit of the range, and includes the exact stated value or range.

As used herein, the term "substantially" refers to a majority or majority, such as at least 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least 99.999%, or even 100%.

As used herein, the term "organic group" refers to any carbon-containing functional group. Exemplary functional groups include oxygen-containing groups such as alkoxy groups, aryloxy groups, aralkyloxy groups, oxo (carbonyl) groups; carboxyl groups including carboxylic acids, carboxylic acid salts, and carboxylic acid esters; sulfur-containing groups such as alkyl and aryl sulfide groups; and other heteroatom-containing groups. Exemplary organic groups include OR, OOR, OC (O) N (R)₂、CN、CF₃、OCF₃R, C (O), methylenedioxy, ethylenedioxy, N (R)₂、SR、SOR、SO₂R、SO₂N(R)₂、SO₃R、C(O)R、C(O)C(O)R、C(O)CH₂C(O)R、C(S)R、C(O)OR、OC(O)R、C(O)N(R)₂、OC(O)N(R)₂、C(S)N(R)₂、(CH₂)_0-2N(R)C(O)R、(CH₂)_0-2N(R)N(R)₂、N(R)N(R)C(O)R、N(R)N(R)C(O)OR、N(R)N(R)CON(R)₂、N(R)SO₂R、N(R)SO₂N(R)₂、N(R)C(O)OR、N(R)C(O)R、N(R)C(S)R、N(R)C(O)N(R)₂、N(R)C(S)N(R)₂、N(COR)COR、N(OR)R、C(＝NH)N(R)₂C (o) n (or) R, C (═ NOR) R, and substituted or unsubstituted (C)₁-C₁₀₀) A hydrocarbyl group, wherein R can be hydrogen (in examples including other carbon atoms) or a carbyl moiety, and wherein the carbyl moiety can be substituted or unsubstituted.

The term "substituted" as used herein in connection with a molecule or organic group as defined herein means that at least one hydrogen atom contained therein is replaced by at least oneA state other than hydrogen atom substitution. As used herein, the term "functional group" or "substituent" refers to a group that can be or is substituted onto a molecule or organic group. Exemplary substituents or functional groups include halogens (e.g., F, Cl, Br, and I); such as the oxygen atoms in the following groups: hydroxyl groups, alkoxy groups, aryloxy groups, aralkoxy groups, oxo (carbonyl) groups, including carboxylic acid, carboxylate salt, and carboxyl groups of carboxylic acid ester; such as the sulfur atom in the following groups: thiol groups, alkyl and aryl thioether groups, sulfoxide groups, sulfone groups, sulfonyl groups and sulfonamide groups; such as the nitrogen atoms in the following groups: amines, hydroxylamines, nitriles, nitro groups, N-oxides, hydrazides, azides, and enamines; and other heteroatoms in various other groups. Exemplary substituents that can be bonded to a substituted carbon (OR other) atom include F, Cl, Br, I, OR, OC (O) N (R)₂、CN、NO、NO₂、ONO₂Azido group, CF₃、OCF₃R, O (oxo), S (thiocarbonyl), C (O), S (O), methylenedioxy, ethylenedioxy, N (R)₂、SR、SOR、SO₂R、SO₂N(R)₂、SO₃R、C(O)R、C(O)C(O)R、C(O)CH₂C(O)R、C(S)R、C(O)OR、OC(O)R、C(O)N(R)₂、OC(O)N(R)₂、C(S)N(R)₂、(CH₂)_0-2N(R)C(O)R、(CH₂)_0-2N(R)N(R)₂、N(R)N(R)C(O)R、N(R)N(R)C(O)OR、N(R)N(R)CON(R)₂、N(R)SO₂R、N(R)SO₂N(R)₂、N(R)C(O)OR、N(R)C(O)R、N(R)C(S)R、N(R)C(O)N(R)₂、N(R)C(S)N(R)₂、N(COR)COR、N(OR)R、C(＝NH)N(R)₂C (o) n (or) R and C (═ NOR) R, where R can be hydrogen or a carbon-based moiety; for example, R can be hydrogen, (C)₁-C₁₀₀) Hydrocarbyl, alkyl, acyl, cycloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, or heteroarylalkyl; or wherein two R groups bonded to a nitrogen atom or to an adjacent nitrogen atom may form a heterocyclic group together with one or more nitrogen atoms.

As used herein, the term "alkyl" refers to straight and branched alkyl groups and cycloalkyl groups having from 1 to 40 (in some embodiments, from 1 to 20, from 1 to 12, or even from 1 to 8) carbon atoms. Exemplary straight chain alkyl groups include those having 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, isobutyl, sec-butyl, tert-butyl, neopentyl, isoamyl, and 2, 2-dimethylpropyl groups. As used herein, the term "alkyl" includes n-alkyl, iso-alkyl, and trans-iso-alkyl groups as well as other branched forms of alkyl. Exemplary substituted alkyl groups can be substituted at least once with any of the groups listed herein (e.g., amino, hydroxyl, cyano, carboxyl, nitro, thio, alkoxy, and halogen groups).

As used herein, the term "aryl" refers to a cyclic aromatic hydrocarbon group that does not contain heteroatoms within the ring. Thus, aryl groups include, but are not limited to, phenyl, azulenyl, cycloheptatrienyl (heptalenyl), biphenyl, dicyclopentadiene acenyl (indacenyl), fluorenyl, phenanthryl, triphenylenyl, pyrenyl, tetracenyl, phenanthrenyl, and phenanthrenyl,

Mesityl, biphenylene, anthracenyl and naphthyl groups. In some embodiments, the aryl group comprises 6 to 14 carbons in the ring portion of the group. The aryl group may be unsubstituted or substituted, as defined herein. Exemplary representative substituted aryl groups can be mono-substituted or substituted more than once, such as a phenyl group substituted in at least any one of the 2-, 3-, 4-, 5-, or 6-positions of the phenyl ring, or a naphthyl group substituted in at least any one of the 2-to 8-positions thereof.

As used herein, the term "heterocyclyl" refers to aromatic and non-aromatic ring compounds containing at least three ring members, at least one of which is a heteroatom, such as N, O and S.

The term "weight average molecular weight" as used herein refers to M_wWhich is equal to sigma M_i ²n_i/ΣM_in_iWherein n is_iIs divided intoQuantum M_iThe number of molecules of (c). In various examples, the weight average molecular weight can be determined using light scattering, small angle neutron scattering, X-ray scattering, and sedimentation velocity. Unless otherwise indicated, molecular weight is weight average molecular weight.

Fig. 1 is a cross-sectional view of an exemplary embodiment of a laminate 10. As shown, the laminate 10 includes a first release liner 12 having an adhesive layer 14 disposed thereon. As further described herein, the first release liner 12 comprises at least one polyolefin component. As further described herein, the adhesive layer 14 can be an optically clear adhesive. The adhesive layer 14 contacts the area of the first release liner 12. This area is defined by the surface area of the major surface of the first release liner 12. As shown, the adhesive layer contacts 100% of the surface area of the major surface of the release liner 12.

Adhesive layer 14 includes openings or incisions 16. As further described herein, the openings 16 may be formed by exposing the laminate 10 to laser electromagnetic radiation. The extent to which the opening 16 extends beyond the adhesive layer 14 and into the first release liner 12, or the extent to which the first release liner 12 is caused to at least partially melt, may be a function of the ability of the respective materials of the first release liner 12 and the adhesive layer 14 to absorb laser electromagnetic radiation. For example, upon exposure to laser electromagnetic radiation, adhesive layer 14 may be configured to absorb at least 55% (in some embodiments at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even 100%) of the laser electromagnetic radiation, while first release liner 12 may absorb no more than 45% (in some embodiments no more than 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or even 0%) of the laser electromagnetic radiation. As further described herein, a difference in absorbance between the first release liner 12 and the adhesive layer 14 may be desirable for a number of reasons.

As described herein, the first release liner 12 comprises at least one polyolefin. The polyolefin may be present in an amount in the range of from 70 wt% to 100 wt% (in some embodiments in the range of from 75 wt% to 100 wt%, from 80 wt% to 100 wt%, from 85 wt% to 100 wt%, from 90 wt% to 100 wt%, or even from 95 wt% to 100 wt%), based on the total weight of the first release liner 12. Exemplary polyolefins may include at least one of polyethylene, polypropylene, polymethylpentene, polybutene-1, polyisobutylene, or copolymers thereof. When the polyolefin is a copolymer, the copolymer may be arranged as a block copolymer, an alternating copolymer, or a random copolymer. The at least one polyolefin may be present as a distribution of polyolefins having different weight average molecular weights.

The polyolefin can have any suitable melt flow index value. Exemplary melt index values may range from 0.1g/10 minutes to 2000g/10 minutes (or in some embodiments from 10g/10 minutes to 1000g/10 minutes, from 100g/10 minutes to 500g/10 minutes, or even from 200g/10 minutes to 300g/10 minutes). As is understood, melt flow index is a measure of the ease of melt flow of a thermoplastic polymer. It is defined as the mass of polymer in grams flowing through a capillary of a particular diameter and length in ten minutes under pressure applied by an alternative specified weighing weight at an alternative specified temperature. For example, for polyethylene polymers, the melt flow index value will be measured using ISO 1133-1 test method at 190 ℃/2.16kg, and for polypropylene, the melt flow index value will be measured using ASTM D1238 at 230 ℃/2.16 kg.

In embodiments where the polyolefin is polyethylene, the polyethylene may have a molecular weight of at 0.80g/cm³To 0.86g/cm³Within the range (in some embodiments at 0.81 g/cm)³To 0.85g/cm³Or even 0.82g/cm³To 0.84g/cm³In range). In additional embodiments, the polyethylene may have a molecular weight at 0.90g/cm³To 0.92g/cm³Within a range (in some embodiments at 0.90 g/cm)³To 0.91g/cm³In range). In further embodiments, the polyethylene may have a molecular weight at 0.92g/cm³To 0.96g/cm³Within the range (in some embodiments at 0.93 g/cm)³To 0.95g/cm³In range).

In embodiments where the polyolefin is polypropylene, the polypropylene may be or include biaxially oriented polypropylene (BOPP). Biaxially oriented polypropylene may be formed by extruding a polypropylene film and stretching the film along two axes oriented at an angle, for example 90 degrees, with respect to each other. The film stretching along the two axes may be sequential or simultaneous. Biaxially oriented polypropylene can improve the strength and clarity of polypropylene.

The material of the first release liner 12 may be selected to optimize the properties of the laminate 10 in forming the openings 16. For this reason, it may be desirable for the first release liner 12 to comprise a polyolefin having a limited ability to absorb laser electromagnetic radiation. As an example, the first release liner 12 may be free of an amount (i.e., at least one weight percent) of at least one polymeric material or additive that would increase the absorbance of the release liner by greater than 5% (in some embodiments, greater than 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or even greater than 95%). In the exemplary first release liner 12, the liner 12 is free of (i.e., less than 1% by weight of the release liner) polyethylene terephthalate.

The adhesive layer 14 may comprise any suitable adhesive. For example, the adhesive may be a pressure sensitive adhesive. Exemplary pressure sensitive adhesives include: a natural rubber-based adhesive, a synthetic rubber-based adhesive, a styrene block copolymer-based adhesive, a polyvinyl ether-based adhesive, a poly (methyl acrylate) -based adhesive, a polyolefin-based adhesive, a polyurethane-based adhesive, a polyester-based adhesive, or a silicone-based adhesive. As used herein, "based on" is meant to include at least 50 weight percent based on the total weight of the adhesive. The remainder of the adhesive may include additives such as tackifiers, plasticizers, oils, or fillers.

Other exemplary adhesives may include the reaction product of a polymerizable mixture including an alkyl acrylate, a polar monomer, and a free radical generating initiator. Exemplary alkyl acrylates (e.g., alkyl acrylate monomers) include at least one of a linear acrylate, branched monofunctional acrylate, or methacrylate of a non-tertiary alkyl alcohol. The alkyl group may have in the range of 1 to 24 carbon atoms. Exemplary monomers includeAt least one of: 2-ethylhexyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, n-nonyl (meth) acrylate, isoamyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isostearyl acrylate, or 2-methylbutyl (meth) acrylate. In one exemplary embodiment, the adhesive layer 14 contains only alkyl (meth) acrylate monomers or styrene monomers with optional vinyl esters. In such cases, the modulus and glass transition temperature (T) of the composition_g) By selecting a low T_gProduction of monomers and high T_gProducing a combination of monomers to adjust. As used herein, the term "glass transition temperature" or "T_g"refers to the temperature at which a polymeric material transitions from a glassy state (e.g., brittleness, hardness, and stiffness) to a rubbery state (e.g., flexible and elastic or viscous). In another exemplary embodiment, the adhesive layer 14 may comprise in the range of 60 to 99 parts by weight (in some embodiments in the range of 65 to 95 parts by weight, or even 70 to 95 parts by weight) of an alkyl (meth) acrylate having in the range of 1 to 24 carbon atoms in the alkyl group.

Exemplary embodiments of the polar monomer may include a polar copolymerizable monomer. Exemplary polar copolymerizable monomers include at least one of: acrylic Acid (AA), methacrylic acid, itaconic acid, fumaric acid, methacrylamide, N-alkyl-and N, N-dialkyl-substituted acrylamides or methacrylamides, wherein the alkyl groups have not more than 3 carbon atoms, N-vinyllactams, (meth) acrylamides, n-morpholino (meth) acrylate, N-vinylpyrrolidone, N-vinylcaprolactam, 2-hydroxy-ethyl (meth) acrylate, 2-hydroxy-propyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-ethoxyethoxyethoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, or combinations thereof. In an exemplary embodiment, adhesive layer 14 includes 1 to 40 parts by weight (in some embodiments 5 to 35 parts by weight, or even 5 to 30 parts by weight) of a polar copolymerizable monomer.

Exemplary free radical generating initiators include at least one of thermal initiators or photoinitiators. Exemplary thermal initiators include peroxides, such as benzoyl peroxide, derivatives thereof, or azo compounds. An exemplary azo compound is 2,2' -azobis- (2-methylbutyronitrile). A wide variety of peroxides or azo compounds are available that can be used to initiate thermal polymerization at a wide range of temperatures. Photoinitiators may be used in place of or in combination with thermal initiators. The one or more initiators may be added to the precursor mixture in an amount of from 0.01 to 2 parts by weight of the polymerizable mixture (in some embodiments, from 0.02 to 1 part by weight, or even from 0.02 to 0.5 parts by weight).

The polymerizable mixture may also include a multifunctional crosslinker. In an exemplary embodiment, the mixture may include a thermal crosslinking agent activated in a drying step of preparing the adhesive layer 14 and a crosslinking agent copolymerized in a polymerization step. Exemplary multifunctional crosslinkers include at least one of a multifunctional isocyanate, a multifunctional aziridine, an epoxy compound, 1, 6-hexanediol diacrylate, an aromatic triisocyanate (available under the trade designation "DESMODUR N3300" from Bayer corporation of Crohn, Bayer, Cologne, Germany)), a benzophenone, or a 4-acryloxybenzophenone. In exemplary embodiments where a crosslinking agent is present, the crosslinking agent may be in the range of 0.01 parts to 5 parts (in some embodiments in the range of 0.01 parts to 4 parts, or even 0.01 parts to 3 parts) of the polymerizable mixture. Other crosslinking methods may be used, such as ionic crosslinking, acid-base crosslinking, or using physical crosslinking methods, such as by copolymerizing high T_gA macromer (e.g., at least one of a polymethylmethacrylate macromer or a polystyrene macromer). MacromoleculesThe monomer may be used in a range of 1 to 20 parts by weight of the total monomer components in the assembly layer composition.

The adhesive layer 14 may be inherently tacky. If desired, a tackifier may be added to the polymerizable mixture prior to forming adhesive layer 14. Exemplary tackifiers include at least one of rosin ester resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, terpenes, or terpene phenolic resins. When included, the tackifier is added to the polymerizable mixture in a range of from 1 to 50 parts by weight of the polymerizable mixture (in some embodiments in a range of from 5 to 45 parts by weight, or even 10 to 30 parts by weight).

In exemplary embodiments, the adhesive layer 14 may be free of (i.e., contain less than 2 parts by weight of the polymerizable mixture) acid, which may help eliminate Indium Tin Oxide (ITO) and metal trace corrosion that may otherwise damage touch sensors and their integrated circuits or connectors.

Exemplary embodiments of the polymerizable mixture may include additional materials such as at least one of molecular weight control agents, coupling agents, oils, plasticizers, antioxidants, UV stabilizers, UV absorbers, pigments, curing agents, polymer additives, or nanoparticles, among other additives. In exemplary embodiments, where the adhesive layer 14 is optically clear (e.g., is an optically clear adhesive), other materials may optionally be added to the monomer mixture so long as they do not significantly reduce the optical clarity of the adhesive layer 14. As used herein, the term "optically transparent" refers to a material having a light transmission greater than 90% and a haze less than 2% over the wavelength range of 400nm to 700 nm. Both light transmission and haze can be measured using, for example, ASTM-D1003-00 (2000). In an exemplary embodiment, the adhesive layer 14 is visually free of air bubbles.

In exemplary embodiments, the polymerizable mixture may be prepolymerized by exposure to heat or actinic radiation to decompose the initiator in the mixture. This may be done prior to the addition of the crosslinking agent and other components to form a coatable syrup to which one or more crosslinking agents, other additives, and additional initiators may be subsequently added. The compounded mixture may then be coated on the first release liner 12 and fully polymerized by additional exposure to ultraviolet radiation under an inert atmosphere. Alternatively, the crosslinking agent, optional additives and initiator may be added to the monomers, and the mixture may be polymerized and cured in one step (e.g., as a liquid optically clear adhesive). The desired coating method and viscosity will determine which process step to use. In another process, the component layer monomer component may be blended with a solvent to form a mixture. The mixture can be polymerized by exposure to heat or actinic radiation (e.g., to decompose an initiator in the mixture). The crosslinking agent and additional additives such as tackifiers and plasticizers may be added to the solvated polymer which may then be coated on a liner and the solvent dried off by an oven to produce a coated adhesive film. The exemplary polymerizable mixture can be applied by any kind of technique known to those skilled in the art, such as roll coating, spray coating, knife coating, or die coating. Fig. 2 is a cross-sectional view of the laminate 10'. The laminate 10' includes a first release liner 12. The laminate 10' also includes an adhesive layer 14. The laminate 10' also includes a second release liner 18. Although shown as a release liner, the second release liner 18 may be replaced by other film layers that are not configured to be removed. Exemplary film layers include optical films. Optical films can intentionally enhance, regulate, control, maintain, transmit, reflect, refract, absorb, retard, or otherwise alter the light projected on the film surface. Films included in the laminate include classes of materials having optical functions such as polarizers, interference polarizers, reflective polarizers, diffusers, colored optical films, mirrors, louvered optical films, light control films, transparent sheets, brightness enhancement films, anti-glare and anti-reflection films, and the like. Films for the provided laminates may also include retardation plates, such as quarter-wave and half-wave phase retardation optical elements. Other optically transparent films include anti-splinter films and electromagnetic interference filters. These films may be cut with laser electromagnetic radiation.

Adhesive layer 14 contacts a portion of second release liner 18. This area is defined by the surface area of the major surface of the second release liner 18. As shown, adhesive layer 14 contacts 100% of the surface area of the major surface of second release liner 18. The second release liner 18 may be chemically the same (i.e., have the same composition, including weight percent components) or different from the first release liner.

The second release liner 18 may be chemically different from the first release liner 12 relative to the first release liner 12. In exemplary embodiments, the second release liner 18 is free of (i.e., less than 1% by weight of the second release liner) at least one polyolefin (e.g., polypropylene). In other exemplary embodiments, the second release liner 18 may comprise polyethylene terephthalate. The second release liner 18 may have an electromagnetic absorbance value that is within at least 20%, in some embodiments within at least 15%, at least 10%, or even within at least 5% of the absorbance value of the adhesive layer 14.

The thickness of at least one of the adhesive layer 14, the first release liner 12, or the second release liner 18, relative to each other, can independently range from 0.012mm to 1.00mm (in some embodiments, from 0.012mm to 0.90mm, from 0.012mm to 0.153mm, from 0.02mm to 0.80mm, from 0.10mm to 0.70mm, from 0.20mm to 0.60mm, or even from 0.30mm to 0.50 mm). Exemplary embodiments of the first release liner 12 or the second release liner 18 may be sufficiently transparent in that either may allow at least 85% (in some embodiments at least 90%, 95%, or 100%) visible light transmittance relative to the adhesive layer 14. In exemplary embodiments, at least one of the first release liner 12 and the second release liner 18 may include a release layer positioned to face the adhesive layer 14. Exemplary release layers may include silicone or fluorinated materials.

Fig. 3 is a cross-sectional view of the electronic device 20. The electronic device 20 includes an adhesive layer 14, the adhesive layer 14 attached to a first substrate 22 and a second substrate 24. Either or both of the first substrate 22 and the second substrate 24 may be replaced with an optical film as described herein. Adhesive layer 14 may be used in conjunction with many different types of electronic devices. However, exemplary electronic devices may be flexible (e.g., foldable or rollable electronic devices). Thus, the

substrates

22 and 24 may be flexible substrates, and the adhesive layer 14 itself may be flexible.

In exemplary embodiments including flexible electronics, the electronics can resist fatigue over thousands of folding cycles over a wide temperature range (such as in the range of-50 ℃ to 100 ℃) from well below or above freezing (in some embodiments in the range of-40 ℃ to 90 ℃, -30 ℃ to 80 ℃, -20 ℃ to 70 ℃, -10 ℃ to 60 ℃,0 ℃ to 50 ℃, 10 ℃ to 40 ℃, or even 20 ℃ to 30 ℃). Furthermore, because the electronic device 20 may be placed statically in the folded state for hours, the adhesive layer 14 has minimal to no creep, thereby preventing significant deformation of the device 20 that can only be partially, if at all, recovered. Such permanent deformation of adhesive layer 14 can result in optical distortion or Mura, which is unacceptable in the display industry. Thus, the adhesive layer 14 is able to withstand the substantial flexural stresses caused by folding the display device as well as withstand high temperature, high humidity (HTHH) testing conditions. In addition, the adhesive layer 14 can have a low storage modulus and high elongation over a wide temperature range (including well below freezing point; therefore, a low glass transition temperature is preferred), and can be crosslinked to produce an elastomer with little or no creep under static load.

During a folding or unfolding event, the adhesive layer 14 may deform significantly and cause stress. The force to resist these stresses may be determined in part by the modulus and thickness of the layers of the apparatus 20, including the adhesive layer 14, the first substrate 22, and the second substrate 24. To ensure low resistance to folding and adequate performance, resulting in minimal stress and good dissipation of stress involved in a bending event, the adhesive layer 14 may have a sufficiently low storage or elastic modulus, typically characterized as shear storage modulus (G'). To further ensure that such behavior remains consistent over the intended use temperature range of such devices, G' may have minimal variation over a wide range of relevant temperatures. In one embodiment, the relevant temperature range is from-30 ℃ to 90 ℃. In one embodiment, the shear modulus is less than 2MPa (in some embodiments less than 1MPa, less than 0.5MPa, or even less than 0.3MPa) throughout the relevant temperature range. Therefore, the temperature of the molten metal is controlled,it is preferable to adjust the glass transition temperature (T)_g) (i.e., the temperature at which the material changes to a glassy state, with a corresponding change in G' to typically greater than 10%⁷The value of Pa) is located outside and below the relevant operating range. In an exemplary embodiment, T of the adhesive layer 14 in the flexible display_gLess than 10 ℃ (in some embodiments less than-10 ℃, or even less than-30 ℃). T may be determined using techniques such as Dynamic Mechanical Analysis (DMA), for example_g。

The thickness of the adhesive layer 14 may be optimized according to the position in the flexible display device. It may be preferable to reduce the thickness of the adhesive layer 14 to reduce the overall thickness of the device and to reduce or minimize buckling, creep, or delamination failure of the composite structure.

The ability of the adhesive layer 14 to absorb flexural stress and to conform to the radically altered geometry of bending or folding may be characterized by the ability of such materials to undergo high amounts of strain or elongation under the relevant applied stress⁶l/Pa (in some embodiments at least 20 × 10⁶1/Pa、50×l0⁶1/Pa, or even 90 × 10⁶l/Pa) shear creep compliance (J). The test may be performed at room temperature (e.g., 25℃.), or may be performed at any temperature relevant to the use of the flexible device.

Adhesive layer 14 may also exhibit relatively low creep to avoid sustained deformation in the multi-layer composite of the display after repeated folding or bending events. Material creep can be determined by simple creep experiments in which a constant shear stress is applied to a material for a given amount of time. Once the stress is removed, recovery of the induced strain is observed. In one embodiment, the shear strain at room temperature within 1 minute after removal of the applied stress (at least one point of applied shear stress in the range of 5kPa to 500 kPa) recovers to at least 50% (in some embodiments at least 60%, 70%, 80%, or even 90%) of the peak strain observed upon application of shear stress. The test is typically performed at room temperature, but may be performed at any temperature relevant to the use of the flexible device. In addition, the ability of the adhesive layer 14 to generate minimal or reduced stress and dissipate stress during a folding or bending event is related to the ability of the adhesive layer 14 to avoid interlayer failure and its ability to protect the more fragile components of the flexible display assembly. Stress generation and dissipation can be determined using conventional stress relaxation testing, in which a material is forced to a relevant amount of shear strain and then held at the relevant amount of shear strain. The amount of shear stress is then observed over time as the material is held at this target strain. In exemplary embodiments, after 500% (in some embodiments 600%, 700%, 800%, or even 900%) strain, the amount of residual stress (measured shear stress divided by peak shear stress) observed after 5 minutes is less than 50% (in some embodiments less than 40%, 30%, 20%, or even 10%) of the peak stress. The test is typically performed at room temperature, but may be performed at any temperature relevant to the use of the flexible device. As an assembly layer, the adhesive layer 14 must adhere sufficiently well to adjacent layers within the display assembly to prevent delamination of the layers during use of the device, including repeated bending and folding actions. While the exact composite layer will be device specific, the general adhesion performance of the component layer can be determined in a conventional 180 degree peel test mode using adhesion to a standard substrate such as polyethylene terephthalate (PET).

When the adhesive layer 14 is placed between

substrates

22 and 24 to form the device 20 and the device 20 is folded or bent and held at the relevant radius of curvature, the laminate may not buckle or delaminate between many use temperatures (e.g., -30 ℃ to 100 ℃), an event that is indicative of material failure in a flexible display device. In exemplary embodiments, the adhesive layer 14 does not exhibit failure when placed within a channel forcing a radius of curvature of less than 200mm (in some embodiments less than 100mm, 50mm, 20mm, 10mm, 5mm, or even 2mm) for a period of time exceeding 24 hours. Furthermore, the device 20 including the adhesive layer 14 of the present invention may not exhibit sustained deformation when removed from the channel and allowed to return from the curved orientation to its previously flat orientation, but may quickly return to a flat or nearly flat orientation. In an exemplary embodiment, the apparatus 20 returns to an almost flat orientation when held for 24 hours and then removed from a channel holding the laminate with a radius of curvature of less than about 50mm (in some embodiments less than 20mm, 10mm, 5mm, or even 3mm), wherein the final angle between the apparatus 20, the point of curvature of the apparatus 20, and the return surface is less than 50 degrees (in some embodiments less than 40 degrees, 30 degrees, 20 degrees, or even 10 degrees) within 1 hour after the laminate is removed from the channel. In other words, the included angle between the flat portions of the folded device 20 is in the range of 0 degrees to an angle of at least 130 degrees (in some embodiments at least 140 degrees, 150 degrees, 160 degrees, or even at least 170 degrees) in the channel 1 hour after the laminate is removed from the channel. This return can be achieved under normal use conditions (including after exposure to durability test conditions).

In addition to the static fold test behavior described herein, a device comprising the first substrate 22 and the second substrate 24 bonded to the adhesive layer 14 may not exhibit failure, such as buckling or delamination, during the dynamic fold simulation test. In one embodiment, the apparatus 20 exhibits no failure events between all use temperatures in a free bend mode (i.e., without the use of a mandrel) in a dynamic folding test of greater than 10,000 (or in some examples greater than 20,000, 40,000, 60,000, 80,000, or even 100,000) cycles folded at a radius of curvature of less than 50mm (or even less than 20mm, 10mm, 5mm, or even 3 mm).

To form the electronic device 20, the first substrate 22 may be applied directly to the adhesive layer 14. In embodiments including laminate 10', after removal of the excess material formed by openings 16, second release liner 18 is removed and first substrate 22 is applied to exposed adhesive layer 14. The first release liner 12 is then removed from the adhesive layer 14 and the second substrate 24 is adhered to the exposed adhesive layer 14. The order in which the

liners

12 and 14 are removed may also be reversed. In exemplary embodiments, the minimum release force required to remove the second release liner 18 from the adhesive layer 14 is in the range of 0.0019N/mm to 0.011N/mm (in some embodiments in the range of 0.0038N/mm to 0.0096N/mm, or even 0.0057N/mm to 0.0077N/mm) less than the minimum release force to remove the first release liner 12 from the adhesive layer 14. In some embodiments, the minimum release force required to remove the first release liner 12 from the adhesive layer 14 is in the range of 0.0019N/mm to 0.011N/mm (in some embodiments in the range of 0.0038N/mm to 0.0096N/mm, or even 0.0057N/mm to 0.0077N/mm) less than the minimum release force to remove the second release liner 18 from the adhesive layer 14. In some embodiments, additional substrates and adhesives may be included to make a multilayer stack. Pressure and/or heat may then be applied to form the flexible laminate.

When removing the first and

second release liners

12 and 18, it may be important to minimize the amount of damage sustained by the adhesive layer 14 during removal of the

liners

12 and 18. For example, it may be desirable to release either of the

liners

12 and 18 so that adhesive from the adhesive layer 14 does not remain on the

liners

12 and 18. The properties of the layer 14 and the apparatus 20 described herein may be altered if some adhesive is removed from the adhesive layer 14. Loss of sheets in the adhesive layer 14 or distortion in the adhesive layer 14 may result in reduced properties (e.g., strength, modulus, or elasticity) or reduced optical properties, such as reduced transparency or optical distortion when light passes through the adhesive.

In some exemplary embodiments, one way to minimize damage is to include a first release liner 12 and a second release liner 18, as described herein. In forming the openings 16, the laminate 10 or 10' may be exposed to a laser electromagnetic radiation source (e.g., a carbon dioxide laser, a carbon monoxide laser, a fiber laser, a laser-based composite laser, or an ultraviolet laser) that generates radiation having a wavelength in the range of 0.10 to 15 (in some embodiments in the range of 0.2 to 14, 0.3 to 13, 8 to 12, or even 9 to 11) to form the openings 16 through at least one of the adhesive layer 14 or the second release liner 18 (if present). The intensity of the laser can be adjusted to the optimum power. The power level of the laser may be in the range of 50W to 400W (or in some embodiments in the range of 100W to 350W, 150W to 300W, or even 200W to 250W). The focal diameter of the laser may be in the range of 150 microns to 300 microns (or in some embodiments in the range of 170 microns to 270 microns, 200 microns to 240 microns, or even 210 microns to 230 microns). Forming the openings 16 may be important for cutting the adhesive layer 14 to an appropriate size or shape. Laser electromagnetic radiation may be applied to at least one of the first layer 12 or the second layer 18.

With the components of the first release liner 12, laser electromagnetic radiation is less likely to be absorbed by the first release liner 12. In an exemplary embodiment, first release liner 12 is free of (i.e., does not include) openings 16 after exposure to the source of laser electromagnetic radiation. This may be accomplished by setting the source of laser electromagnetic radiation at a power level sufficient to create openings 16 in at least one of adhesive layer 14 and second release liner 18. However, the power of the laser electromagnetic radiation source may be adjusted so that the opening 16 does extend into the first release liner 12. The power of the laser electromagnetic radiation source may be further adjusted so that the openings 16 do extend into the first release liner 12, but by virtue of the components of the liner 12, the openings 16 extend into the first release liner 12 to a lesser extent than a corresponding first release liner that does not contain (i.e., does not contain) at least one polyolefin or contains polyethylene terephthalate.

Regardless of whether the openings 16 extend into the first release liner, forming the openings 16 in the polyolefin-containing or polyethylene terephthalate-free laminate 10 or laminate 10' reduces or substantially eliminates the tendency of the first release liner 12 to melt and subsequently bond to the adhesive layer 14. Reducing or eliminating the tendency of the first release liner 12 to melt may include melting less than 5 weight percent of the material of the first release liner. With less melting, the tendency of the first release liner 12 and the adhesive layer 14 to increase their bonding is reduced. That is, by including a polyolefin such as polypropylene in the first release liner 12, as opposed to a material such as polyethylene terephthalate, the openings 16 extend into the first release liner 12 to a lesser extent and the tendency to form a stronger bond between the first release liner 12 and the adhesive layer 14 is reduced. This is shown in fig. 4 and 5, respectively. Fig. 4 is a photograph of a laminate 10' in which the first liner 12 comprises polypropylene and the openings 16 do not penetrate into the first release liner 12, nor is there significant interfacial distortion between the first release liner 12 and the adhesive layer (which would enhance bond strength). In contrast, fig. 5 is a photograph of an alternative laminate 10 "in which the first release liner 12 'comprises polyethylene terephthalate and is exposed to the same laser electromagnetic radiation power for the same amount of time as laminate 10 or laminate 10'. As shown, the opening 16 extends into the first release liner 12 'and there is significant interfacial distortion between the first release liner 12' and the adhesive layer 14.

The opening 16 may be continuous and, in exemplary embodiments, may have a geometry selected from the group consisting of circular, oval, elliptical, triangular, square, rectangular, trapezoidal, pentagonal, hexagonal, heptagonal, octagonal, or any other high-order polygon. Alternatively, the openings 16 may be discontinuous and located at predetermined locations in the laminate 10 or laminate 10'.

The present invention provides the following exemplary embodiments, the numbering of which should not be construed as specifying the degree of importance:

a laminate comprising:

a release liner comprising at least one polyolefin; and

The laminate of exemplary embodiment 1A, wherein the at least one polyolefin is present in an amount in the range of from 70 wt% to 100 wt% (in some embodiments in the range of from 75 wt% to 100 wt%, 80 wt% to 100 wt%, 85 wt% to 100 wt%, 90 wt% to 100 wt%, or even 95 wt% to 100 wt%), based on the total weight of the release liner.

The laminate of exemplary embodiments 1A or 2A, wherein the at least one polyolefin is at least one of polyethylene, polypropylene, polymethylpentene, polybutene-1, polyisobutylene, or copolymers thereof.

The laminate of exemplary embodiment 3A, wherein the polyethylene has a density of between 0.80g/cm³To 0.86g/cm³Within the range (in some embodiments at 0.81 g/cm)³To 0.85g/cm³Or even 0.82g/cm³To 0.84g/cm³In range).

The laminate of exemplary embodiment 3A, wherein the polyethylene has a density of between 0.90g/cm³To 0.92g/cm³Within a range (in some embodiments at 0.90 g/cm)³To 0.91g/cm³In range).

The laminate of exemplary embodiment 3A, wherein the polyethylene has a density of between 0.92g/cm³To 0.96g/cm³Within the range (in some embodiments at 0.93 g/cm)³To 0.95g/cm³In range).

The laminate of exemplary embodiment 3A, wherein the polypropylene comprises biaxially oriented polypropylene.

The laminate of any of the foregoing a exemplary embodiments, wherein the release liner allows at least 85% (in some embodiments at least 90%, 95%, or 100%) visible light transmittance.

The laminate of any of the foregoing a exemplary embodiments, wherein the release liner is free of an amount (i.e., at least one weight percent) of at least one polymeric material or additive that would increase the absorbance of the release liner by greater than 5% (in some embodiments greater than 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or even greater than 95%) of the laser electromagnetic radiation.

The laminate of any of the foregoing example embodiments a, wherein the release liner is free of (i.e., less than 1% by weight of the release layer) polyethylene terephthalate.

The laminate of any of the foregoing a exemplary embodiments, further comprising a film layer, wherein a portion of the adhesive layer is in contact with a region of the film layer.

The laminate of exemplary embodiment 11A, wherein the film layer is an optical film.

The laminate of any of the foregoing a exemplary embodiments, wherein the release liner is a first release liner and the film layer is a second release liner, and wherein a portion of the adhesive layer is in contact with an area of a major surface of the second release liner.

The laminate of exemplary embodiment 13A, wherein the second release liner is chemically the same (i.e., comprises the same weight percentage of components) or different from the first release liner.

The laminate of exemplary embodiment 14A, wherein the second release liner is chemically different (i.e., comprises at least one component that differs by at least 0.5 wt.%) from the first release liner.

The laminate of any of exemplary embodiments 14A-15A, wherein the second release liner is free of (i.e., less than 1 wt% of the second release liner) polyolefin.

The laminate of any of exemplary embodiments 14A-16A, wherein the second release liner is free of (i.e., less than 1 wt.% of the second release liner) polypropylene.

The laminate of any of exemplary embodiments 14A-17A, wherein the second release liner has an absorbance value within at least 20% (in some embodiments at least 15%, 10%, or even at least 5%) of the absorbance value of the adhesive layer.

The laminate of any of the preceding a exemplary embodiments, wherein both the first release liner and the second release liner comprise a release layer positioned to face the adhesive layer.

The laminate of exemplary embodiment 19A, wherein the release layer comprises at least one of a polysiloxane or a fluorinated compound.

The laminate of any of the foregoing a exemplary embodiments, wherein the adhesive layer comprises at least one of a natural rubber-based adhesive, a synthetic rubber-based adhesive, a styrene block copolymer-based adhesive, a polyvinyl ether-based adhesive, a poly (methyl acrylate) -based adhesive, a polyolefin-based adhesive, a polyurethane-based adhesive, a polyester-based adhesive, or a silicone-based adhesive (where "based on" means containing at least 50 wt% based on the total weight of the adhesive).

The laminate of any of the foregoing exemplary embodiments of a, wherein the adhesive layer is a reaction product of a polymerizable mixture comprising:

at least one alkyl acrylate;

at least one polar monomer; and

at least one initiator that generates free radicals.

The laminate of any of the foregoing a exemplary embodiments, wherein the adhesive layer is an optically clear adhesive layer.

The laminate of any one of exemplary embodiments 22A or 23A, wherein the alkyl acrylate comprises in the range of 1 to 24 (in some embodiments in the range of 2 to 23, 3 to 22, 4 to 21, 5 to 20, 6 to 19, 7 to 18, 8 to 17, 9 to 16, 10 to 15, 9 to 14, or even 11 to 13) carbon atoms in the alkyl group.

The laminate of any one of exemplary embodiments 22A-24A, wherein the adhesive has a glass transition temperature, and wherein the glass transition temperature is in a range of-50 ℃ to 20 ℃ (in some embodiments in a range of-40 ℃ to 20 ℃, -30 ℃ to 20 ℃, -20 ℃ to 20 ℃, -10 ℃ to 10 ℃, or even-5 ℃ to 5 ℃).

The laminate of any one of exemplary embodiments 22A to 25A, wherein the polar monomer is a copolymerizable polar monomer.

The laminate of exemplary embodiment 26A, wherein the at least one polar copolymerizable monomer is at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, methacrylamide, N-alkylacrylamide, N-dialkylacrylamide, N-alkylmethacrylamide, N-dialkylmethacrylamide, N-vinyllactam, hydroxyalkyl (meth) acrylate, or hydroxyalkyl (meth) acrylamide.

The laminate of any of the foregoing a exemplary embodiments, wherein the adhesive, the first release liner, or the second release liner independently have a thickness in the range of 0.012mm to 1.00mm (or in some embodiments in the range of 0.012mm to 0.90mm, 0.012mm to 0.153mm, 0.02mm to 0.80mm, 0.10mm to 0.70mm, 0.20mm to 0.60mm, or even 0.30mm to 0.50 mm).

A method of treating the laminate of any of the foregoing exemplary embodiments a, comprising:

exposing the laminate to a source of laser electromagnetic radiation having a wavelength in the range of 0.10 to 15 (in some embodiments in the range of 0.2 to 14, 0.3 to 13, 8 to 12, or even 9 to 11) to form an opening through at least one of the adhesive or the second release liner.

The method of exemplary embodiment 1B, wherein the first release liner is free of (i.e., does not include) openings.

The method of any of exemplary embodiments 1B or 2B, wherein the opening extends into the thickness of the first release liner to a lesser extent than a corresponding first release liner that does not contain (i.e., does not contain) at least one polyolefin.

The method of any of the preceding B exemplary embodiments, wherein the opening extends into the thickness of the first release liner to a lesser extent than a corresponding first release liner without polypropylene.

The method of any of the preceding B exemplary embodiments, wherein the opening extends into the thickness of the first release liner to a lesser extent than a corresponding first release liner comprising polyethylene terephthalate.

The method of any of the preceding B exemplary embodiments, wherein the first release liner has a lower degree of melting than a corresponding release liner comprising polyethylene terephthalate when exposed to the laser electromagnetic radiation.

The method of any of the preceding B exemplary embodiments, wherein the first release liner does not melt (i.e., less than 5 wt.% of the material of the first release liner) during exposure to laser electromagnetic radiation.

The method of any of the preceding B exemplary embodiments, wherein the opening is continuous and has at least one geometric shape.

The method of exemplary embodiment 8B, wherein the geometric shape is a circle, an oval, an ellipse, a triangle, a square, a rectangle, a trapezoid, a pentagon, a hexagon, a heptagon, an octagon, or any other high order polygon.

The method of any of the preceding B exemplary embodiments, wherein the laser electromagnetic radiation is provided by at least one of a carbon dioxide laser, a carbon monoxide laser, a fiber laser, an exciplex laser, or an ultraviolet laser.

The method of any of the preceding B exemplary embodiments, comprising removing the second release liner to expose the adhesive and applying a first substrate to the adhesive.

The method of exemplary embodiment 11B, further comprising removing the first release liner to expose the adhesive and applying a second substrate to the adhesive to form an electronic device.

The method of any of exemplary embodiments 11B or 12B, wherein the minimum release force required to remove the second release liner from the adhesive layer is in the range of 0.0019N/mm to 0.011N/mm (in some embodiments in the range of 0.0038N/mm to 0.0096N/mm, or even 0.0057N/mm to 0.0077N/mm) less than the minimum release force to remove the first release liner from the adhesive layer.

The method of exemplary embodiment 13B, wherein the minimum release force required to remove the first release liner from the adhesive layer is in the range of 0.0019N/mm to 0.011N/mm (in some embodiments in the range of 0.0038N/mm to 0.0096N/mm, or even 0.0057N/mm to 0.0077N/mm) less than the minimum release force to remove the second release liner from the adhesive layer.

15b. the method of any one of exemplary embodiments 12B-14B, wherein at least one of the first substrate or the second substrate is a flexible substrate.

An electronic device comprising a substrate formed according to the method of any one of exemplary embodiments 10B-13B.

The electronic device of exemplary embodiment 1C, wherein the electronic device is a flexible electronic display.

The electronic device of any of example embodiments 1C or 2C, wherein the electronic device does not exhibit failure (e.g., buckling or delamination) when placed within a channel forcing a radius of curvature of less than 15mm (in some embodiments, less than 10mm, 5mm, or even less than 1mm) for a period of more than 24 hours at room temperature.

The electronic device of exemplary embodiment 3C, wherein the electronic device does not exhibit failure (e.g., buckling or delamination) when subjected to a dynamic folding test of 10,000 cycles with a radius of curvature of less than 15mm (in some embodiments less than 10mm, 5mm, or even less than 1mm) folding at room temperature.

Examples

Various embodiments of the present invention may be better understood by reference to the following examples, which are provided by way of illustration. The present invention is not limited to the examples given herein.

Preparation of laminates

Example 1

Adhesive layer 14 is a 25 micron acrylic foldable assembly layer as described in PCT patent publication No. wo 2016/196541(Behling et al), the disclosure of which is incorporated herein by reference, under the heading "examples 7-20: based on the preparation of solvent-free assembly layer samples ", and the details are those of example 8 in table 3. The adhesive is in the form of a laminate 10' between a 75 micron silicone coated low release second liner 18 (composite will be device specific) adhered to a standard substrate such as Polyethylene (PET) (obtained under the trade designation "RF 02N" from SKC Haas (skcha as, Seoul, South Korea) by Seoul, Korea) and a 100 micron addition cured silicone release coated biaxially oriented polypropylene (BOPP) low release first liner 12.

The laminate was exposed to sufficient laser electromagnetic radiation to produce a 25.4mm × 203.2.2 mm rectangular continuous profile cut through the second release liner 18 and adhesive layer 14, shown in elevation section as opening 16 in fig. 2, using 9.4 microns of CO₂A laser (available under the trade designation "DIAMOND E-400-I" from cowhernt, inc., Bloomfield, CT) was set up to make the appropriate cuts.

The portions of the adhesive layer 14 and the second release liner 18 that were outside the rectangular continuous outline were then removed by hand from the first release liner 12, leaving a 25.4mm × 203.2.2 mm rectangle of the second release liner 18 and adhesive layer 14 on top of the large panel of the first release liner 12.

Example 2

Example 2 was prepared as described in example 1 except that the adhesive was in the form of laminate 10' between 75 micron silicone coated PET low release second liner 18(RF02N) and 100 micron addition cured silicone release coated BOPP high release first liner 12.

Example 3

Example 3 was prepared as described in example 1, except that the adhesive was in the form of laminate 10 "between 75 micron silicone coated PET low release second liner 18(RF02N) and 75 micron silicone coated PET high release first liner 12 (available from SKC Haas under the trade designation" RF12N ").

Comparative example C-1

The laminate was prepared as described in example 1 for comparative example C-1, however, rather than cutting the laminate with a laser, the laminate was flat die cut in a die cutting press (obtained under the trade designation "MP-200 SR" from akabano major industries co., ltd., Konosu, Japan) using a die having an edge angle of 30 degrees (obtained under the trade designation "flexibile PINNACLE DIE" from kakakamurkamur kukamur gmg.co., ltd., Osaka, Japan) to produce a 57mm × 121mm rectangular continuous profile cut through the second release liner 18 and adhesive layer 14. this is shown in front view as opening 16 in fig. 2. care is taken to leave a slight die mark on the first release liner 12.

The portions of the adhesive layer 14 and the second release liner 18 that were outside the rectangular continuous outline were then removed by hand from the first release liner 12, leaving a 57mm × 121mm rectangle of the second release liner 18 and adhesive layer 14 on top of the large panel of the first release liner 12.

A summary of the above laminates is provided in table 1 below.

TABLE 1

Measurement of force to peel the second liner from the adhesive

The laminate 10' of the sample of the example was adhered to a glass plate with a 2kg roller using double-sided tape (obtained under the trade designation "3M # 410" from 3M Company, st. paul, MN, st.) between the first release liner 12 and the glass plate. The second release liner 18 was then removed at a 90 degree angle at a speed of 2.286 meters per minute using a slide/peel tester (available under the trade designation "IMASS SP-2100" from alcoded IMASS corporation, IMASS, inc., accurate, MA). The average steady state release force of the second release liner 18 from the adhesive layer 14 was recorded.

The results of the second release liner 18 removal test are provided in table 2 below.

TABLE 2

Examples	Number of test samples	Average second Release liner 18 Steady State Release force (g/25.4 mm)
			1	2	17.09
2	1	16.79
			3	1	14.8
C-1	10	Can not measure

For comparative example C-1 (die cut sample), the release force of the second release liner 18 was close to the release force of the first release liner 12. Therefore, so-called pad confusion may occur. Liner confusion refers to the situation where the adhesive cannot be left exclusively with one of the liners during the peel test. Peeling may occur at unintended interfaces due to the similar forces required to peel at the interface of the two adhesives. For comparative example C-1, ten samples were peeled and all ten samples showed at least some removal of the adhesive from the unintended interface. For example 1, ten more samples were peeled off, and none of the samples showed removal of the adhesive from the unintended interface. For examples 1 to 3, the greater force required to begin removal of the first liner 12 at the opening 16 (shown below) prevents the occurrence of liner aliasing.

The force to peel the first liner 12 from the adhesive layer 14 was measured at the opening 16 and at steady state

On the sample of the example, the second release liner 18 was removed from the adhesive layer 14, and the adhesive was then laminated to the glass substrate using a 2kg roller. The first release liner 12 was then removed at a speed of 2.286 meters/minute using a slide/peel tester (IMASS SP-2100) at a 90 degree angle. Ten samples were tested per example. The initial force required to separate the first release liner 12 from the adhesive layer 14 at the opening 16 and the average steady state release force required to continue to remove the first release liner 12 from the adhesive layer 14 away from the opening 16 were recorded.

The results of the release liner removal test are provided in table 3 below.

TABLE 3

The sample of comparative example C-1 could not be tested due to pad confusion.

Although the terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the embodiments of the invention. Thus, it should be understood that although the present invention has been specifically disclosed by particular embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of embodiments of this invention.

Claims

1. A laminate, comprising:

a release liner comprising at least one polyolefin; and

an adhesive layer contacting an area of the first major surface of the release liner,

wherein upon exposure to laser electromagnetic radiation, the adhesive layer is configured to absorb at least 55% of the laser electromagnetic radiation and the release liner absorbs no greater than 45% of the laser electromagnetic radiation.

2. The laminate of claim 1, wherein the at least one polyolefin is at least one of polyethylene, polypropylene, polymethylpentene, polybutene-1, polyisobutylene, or copolymers thereof.

3. The laminate of any one of claims 1 or 2, wherein the release liner is free of at least one polymeric material or additive that absorbs greater than 5% of the laser electromagnetic radiation.

4. The laminate of any one of claims 1 to 3, wherein the release liner is free of polyethylene terephthalate.

5. The laminate of any one of claims 1-4, wherein the release liner is a first release liner, and the laminate further comprises at least one of an optical film or a second release liner, and wherein a portion of the adhesive layer contacts an area of a major surface of the optical film or second release liner.

6. The laminate of any one of claims 1 to 5, wherein the second release liner is free of polyolefin.

7. The laminate of any one of claims 1 to 6, wherein the adhesive layer is a reaction product of a polymerizable mixture comprising:

at least one alkyl acrylate;

at least one polar monomer; and

at least one initiator that generates free radicals.

8. A method of processing a laminate, the method comprising:

providing or receiving a laminate comprising:

a release liner comprising at least one polyolefin; and

an adhesive layer contacting an area of the first major surface of the release liner; and

exposing the laminate to a source of laser electromagnetic radiation having a wavelength in a range of 0.1 to 15 microns to form an opening through at least one of the adhesive or the second release liner, wherein upon exposure to laser electromagnetic radiation, the adhesive layer is configured to absorb at least 55% of the laser electromagnetic radiation and the release liner absorbs no greater than 45% of the laser electromagnetic radiation.

9. The method of claim 8, wherein the first release liner is free of the openings.

10. The method of any of claims 8 or 9, wherein the opening extends into the thickness of the first release liner to a lesser extent than a corresponding first release liner without the at least one polyolefin.

11. The method of any of claims 8-10, wherein the opening extends into the thickness of the first release liner to a lesser extent than a corresponding first release liner without polypropylene.

12. The method of any of claims 8-11, wherein the opening extends into the thickness of the first release liner to a lesser extent than a corresponding first release liner comprising polyethylene terephthalate.

13. The method of any of claims 8-12, wherein the first release liner has a lower melt content than a corresponding release liner comprising polyethylene terephthalate when exposed to the laser electromagnetic radiation.

14. The method of any of claims 8-13, wherein the first release liner does not melt during exposure to the laser electromagnetic radiation.

15. The method of any one of claims 8 to 14, wherein the minimum release force required to remove the second release liner from the adhesive layer is in the range of 0.0019N/mm to 0.011N/mm less than the minimum release force to remove the first release liner from the adhesive layer.